A variety of diagnostic tests (including angiography, CT scanning, and noninvasive cardiac and vascular tests) are available for the study of the stroke patient. These tests vary with respect to cost, discomfort, and risk of complication. We propose to investigate the utility of each of these tests in establishing stroke cause. Deciding on stroke cause is essential to planning effective therapy. Furthermore, we will examine the utility of these tests in predicting survival, rate and degree of recovery, and risk of stroke recurrence. We also propose to establish those circumstances in which each test is likely to be helpful and those instances in which the test should be deferred because of low ratio of benefit to either cost or risk of complications. Study designs and analysis plans have been formulated for this project.